I take no issue with anyone who chooses to side-step poisonous snakes and let them live.
Speaking for myself, I only see poisonous snakes in places that I frequent for hunting...including trips scouting, building blinds, putting up stands, and hunting trips themselves.
That means I'm repeatedly going back in to places where I've seen poisonous snakes...and to me, intentionally letting one live is like seeing a land mine and not diffusing it, then accidentally stepping on it next time I'm in there.
I don't bother any non-poisonous snakes like black snakes, green snakes, garden snakes, etc, etc...but if I see a poisonous snake in the places I frequent, I will kill it.
And in case that sounds like I kill a lot of poisonous snakes, I've only killed two in over a half a century.